Tools for inserting and removing heavy studs used to fasten the cover on nuclear reactor pressure vessels must be capable of handling stud assemblies weighing up to 1000 lbs. Because of the weight of these studs, the stud threads have a tendency to bind unless an upward preload is applied to the stud during the removing and inserting operation. Most prior art tools use sets of springs to apply this preload and rotate the stud with a leadscrew and nut arrangement. In this approach the leadscrew and nut arrangement must have the same thread pitch as the stud in order to maintain a constant preload for the full travel of the stud as it is threaded into or out of the pressure vessel cover flange. Thus, these tools are limited to use on studs having the same pitch unless the leadscrew assembly is changed. These prior art tools are also inherently slow to operate since the leadscrew nut must be threaded back to the opposite end of its travel to position it for the next stud. And lastly, the size and number of springs required varies with the size of the stud, thus requiring a time consuming change of springs, or the use of different tool for each stud size.
Because of the inherent problems associated with the use of the prior art tools for inserting and removing heavy studs, it has become desirable to develop a tool that can be used on any number of different sizes of studs and which will apply an upward preload to the stud in order to prevent the threads formed thereon from binding in the threaded bore into which the stud is inserted and removed.